<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT    MIT License
 * @link    http://codeigniter.com
 * @since    Version 1.4.1
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * oci8 Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package        CodeIgniter
 * @subpackage  Drivers
 * @category    Database
 * @author        EllisLab Dev Team
 * @link        http://codeigniter.com/user_guide/database/
 */

/**
 * oci8 Database Adapter Class
 *
 * This is a modification of the DB_driver class to
 * permit access to oracle databases
 *
 * @author      Kelly McArdle
 */
class CI_DB_oci8_driver extends CI_DB {

    /**
     * Database driver
     *
     * @var    string
     */
    public $dbdriver = 'oci8';

    /**
     * Statement ID
     *
     * @var    resource
     */
    public $stmt_id;

    /**
     * Cursor ID
     *
     * @var    resource
     */
    public $curs_id;

    /**
     * Commit mode flag
     *
     * @var    int
     */
    public $commit_mode = OCI_COMMIT_ON_SUCCESS;

    /**
     * Limit used flag
     *
     * If we use LIMIT, we'll add a field that will
     * throw off num_fields later.
     *
     * @var    bool
     */
    public $limit_used;

    // --------------------------------------------------------------------

    /**
     * List of reserved identifiers
     *
     * Identifiers that must NOT be escaped.
     *
     * @var    string[]
     */
    protected $_reserved_identifiers = array('*', 'rownum');

    /**
     * ORDER BY random keyword
     *
     * @var    array
     */
    protected $_random_keyword = array('ASC', 'ASC'); // not currently supported

    /**
     * COUNT string
     *
     * @used-by    CI_DB_driver::count_all()
     * @used-by    CI_DB_query_builder::count_all_results()
     *
     * @var    string
     */
    protected $_count_string = 'SELECT COUNT(1) AS ';

    // --------------------------------------------------------------------

    /**
     * Class constructor
     *
     * @param    array    $params
     * @return    void
     */
    public function __construct($params)
    {
        parent::__construct($params);

        $valid_dsns = array(
            'tns'    => '/^\(DESCRIPTION=(\(.+\)){2,}\)$/', // TNS
            // Easy Connect string (Oracle 10g+)
            'ec'    => '/^(\/\/)?[a-z0-9.:_-]+(:[1-9][0-9]{0,4})?(\/[a-z0-9$_]+)?(:[^\/])?(\/[a-z0-9$_]+)?$/i',
            'in'    => '/^[a-z0-9$_]+$/i' // Instance name (defined in tnsnames.ora)
        );

        /* Space characters don't have any effect when actually
         * connecting, but can be a hassle while validating the DSN.
         */
        $this->dsn = str_replace(array("\n", "\r", "\t", ' '), '', $this->dsn);

        if ($this->dsn !== '')
        {
            foreach ($valid_dsns as $regexp)
            {
                if (preg_match($regexp, $this->dsn))
                {
                    return;
                }
            }
        }

        // Legacy support for TNS in the hostname configuration field
        $this->hostname = str_replace(array("\n", "\r", "\t", ' '), '', $this->hostname);
        if (preg_match($valid_dsns['tns'], $this->hostname))
        {
            $this->dsn = $this->hostname;
            return;
        }
        elseif ($this->hostname !== '' && strpos($this->hostname, '/') === FALSE && strpos($this->hostname, ':') === FALSE
            && (( ! empty($this->port) && ctype_digit($this->port)) OR $this->database !== ''))
        {
            /* If the hostname field isn't empty, doesn't contain
             * ':' and/or '/' and if port and/or database aren't
             * empty, then the hostname field is most likely indeed
             * just a hostname. Therefore we'll try and build an
             * Easy Connect string from these 3 settings, assuming
             * that the database field is a service name.
             */
            $this->dsn = $this->hostname
                .(( ! empty($this->port) && ctype_digit($this->port)) ? ':'.$this->port : '')
                .($this->database !== '' ? '/'.ltrim($this->database, '/') : '');

            if (preg_match($valid_dsns['ec'], $this->dsn))
            {
                return;
            }
        }

        /* At this point, we can only try and validate the hostname and
         * database fields separately as DSNs.
         */
        if (preg_match($valid_dsns['ec'], $this->hostname) OR preg_match($valid_dsns['in'], $this->hostname))
        {
            $this->dsn = $this->hostname;
            return;
        }

        $this->database = str_replace(array("\n", "\r", "\t", ' '), '', $this->database);
        foreach ($valid_dsns as $regexp)
        {
            if (preg_match($regexp, $this->database))
            {
                return;
            }
        }

        /* Well - OK, an empty string should work as well.
         * PHP will try to use environment variables to
         * determine which Oracle instance to connect to.
         */
        $this->dsn = '';
    }

    // --------------------------------------------------------------------

    /**
     * Non-persistent database connection
     *
     * @param    bool    $persistent
     * @return    resource
     */
    public function db_connect($persistent = FALSE)
    {
        $func = ($persistent === TRUE) ? 'oci_pconnect' : 'oci_connect';
        return empty($this->char_set)
            ? $func($this->username, $this->password, $this->dsn)
            : $func($this->username, $this->password, $this->dsn, $this->char_set);
    }

    // --------------------------------------------------------------------

    /**
     * Database version number
     *
     * @return    string
     */
    public function version()
    {
        if (isset($this->data_cache['version']))
        {
            return $this->data_cache['version'];
        }

        if ( ! $this->conn_id OR ($version = oci_server_version($this->conn_id)) === FALSE)
        {
            return FALSE;
        }

        return $this->data_cache['version'] = $version;
    }

    // --------------------------------------------------------------------

    /**
     * Execute the query
     *
     * @param    string    $sql    an SQL query
     * @return    resource
     */
    protected function _execute($sql)
    {
        /* Oracle must parse the query before it is run. All of the actions with
         * the query are based on the statement id returned by oci_parse().
         */
        $this->stmt_id = FALSE;
        $this->_set_stmt_id($sql);
        oci_set_prefetch($this->stmt_id, 1000);
        return oci_execute($this->stmt_id, $this->commit_mode);
    }

    // --------------------------------------------------------------------

    /**
     * Generate a statement ID
     *
     * @param    string    $sql    an SQL query
     * @return    void
     */
    protected function _set_stmt_id($sql)
    {
        if ( ! is_resource($this->stmt_id))
        {
            $this->stmt_id = oci_parse($this->conn_id, $sql);
        }
    }

    // --------------------------------------------------------------------

    /**
     * Get cursor. Returns a cursor from the database
     *
     * @return    resource
     */
    public function get_cursor()
    {
        return $this->curs_id = oci_new_cursor($this->conn_id);
    }

    // --------------------------------------------------------------------

    /**
     * Stored Procedure.  Executes a stored procedure
     *
     * @param    string    package name in which the stored procedure is in
     * @param    string    stored procedure name to execute
     * @param    array    parameters
     * @return    mixed
     *
     * params array keys
     *
     * KEY      OPTIONAL    NOTES
     * name        no    the name of the parameter should be in :<param_name> format
     * value    no    the value of the parameter.  If this is an OUT or IN OUT parameter,
     *                this should be a reference to a variable
     * type        yes    the type of the parameter
     * length    yes    the max size of the parameter
     */
    public function stored_procedure($package, $procedure, $params)
    {
        if ($package === '' OR $procedure === '' OR ! is_array($params))
        {
            log_message('error', 'Invalid query: '.$package.'.'.$procedure);
            return ($this->db_debug) ? $this->display_error('db_invalid_query') : FALSE;
        }

        // build the query string
        $sql = 'BEGIN '.$package.'.'.$procedure.'(';

        $have_cursor = FALSE;
        foreach ($params as $param)
        {
            $sql .= $param['name'].',';

            if (isset($param['type']) && $param['type'] === OCI_B_CURSOR)
            {
                $have_cursor = TRUE;
            }
        }
        $sql = trim($sql, ',').'); END;';

        $this->stmt_id = FALSE;
        $this->_set_stmt_id($sql);
        $this->_bind_params($params);
        return $this->query($sql, FALSE, $have_cursor);
    }

    // --------------------------------------------------------------------

    /**
     * Bind parameters
     *
     * @param    array    $params
     * @return    void
     */
    protected function _bind_params($params)
    {
        if ( ! is_array($params) OR ! is_resource($this->stmt_id))
        {
            return;
        }

        foreach ($params as $param)
        {
            foreach (array('name', 'value', 'type', 'length') as $val)
            {
                if ( ! isset($param[$val]))
                {
                    $param[$val] = '';
                }
            }

            oci_bind_by_name($this->stmt_id, $param['name'], $param['value'], $param['length'], $param['type']);
        }
    }

    // --------------------------------------------------------------------

    /**
     * Begin Transaction
     *
     * @param    bool    $test_mode
     * @return    bool
     */
    public function trans_begin($test_mode = FALSE)
    {
        if ( ! $this->trans_enabled)
        {
            return TRUE;
        }

        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ($this->_trans_depth > 0)
        {
            return TRUE;
        }

        // Reset the transaction failure flag.
        // If the $test_mode flag is set to TRUE transactions will be rolled back
        // even if the queries produce a successful result.
        $this->_trans_failure = ($test_mode === TRUE);

        $this->commit_mode = is_php('5.3.2') ? OCI_NO_AUTO_COMMIT : OCI_DEFAULT;
        return TRUE;
    }

    // --------------------------------------------------------------------

    /**
     * Commit Transaction
     *
     * @return    bool
     */
    public function trans_commit()
    {
        if ( ! $this->trans_enabled)
        {
            return TRUE;
        }

        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ($this->_trans_depth > 0)
        {
            return TRUE;
        }

        $this->commit_mode = OCI_COMMIT_ON_SUCCESS;
        return oci_commit($this->conn_id);
    }

    // --------------------------------------------------------------------

    /**
     * Rollback Transaction
     *
     * @return    bool
     */
    public function trans_rollback()
    {
        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
        {
            return TRUE;
        }

        $this->commit_mode = OCI_COMMIT_ON_SUCCESS;
        return oci_rollback($this->conn_id);
    }

    // --------------------------------------------------------------------

    /**
     * Affected Rows
     *
     * @return    int
     */
    public function affected_rows()
    {
        return oci_num_rows($this->stmt_id);
    }

    // --------------------------------------------------------------------

    /**
     * Insert ID
     *
     * @return    int
     */
    public function insert_id()
    {
        // not supported in oracle
        return $this->display_error('db_unsupported_function');
    }

    // --------------------------------------------------------------------

    /**
     * Show table query
     *
     * Generates a platform-specific query string so that the table names can be fetched
     *
     * @param    bool    $prefix_limit
     * @return    string
     */
    protected function _list_tables($prefix_limit = FALSE)
    {
        $sql = 'SELECT "TABLE_NAME" FROM "ALL_TABLES"';

        if ($prefix_limit !== FALSE && $this->dbprefix !== '')
        {
            return $sql.' WHERE "TABLE_NAME" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
                .sprintf($this->_like_escape_str, $this->_like_escape_chr);
        }

        return $sql;
    }

    // --------------------------------------------------------------------

    /**
     * Show column query
     *
     * Generates a platform-specific query string so that the column names can be fetched
     *
     * @param    string    $table
     * @return    string
     */
    protected function _list_columns($table = '')
    {
        if (strpos($table, '.') !== FALSE)
        {
            sscanf($table, '%[^.].%s', $owner, $table);
        }
        else
        {
            $owner = $this->username;
        }

        return 'SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS
            WHERE UPPER(OWNER) = '.$this->escape(strtoupper($owner)).'
                AND UPPER(TABLE_NAME) = '.$this->escape(strtoupper($table));
    }

    // --------------------------------------------------------------------

    /**
     * Returns an object with field data
     *
     * @param    string    $table
     * @return    array
     */
    public function field_data($table)
    {
        if (strpos($table, '.') !== FALSE)
        {
            sscanf($table, '%[^.].%s', $owner, $table);
        }
        else
        {
            $owner = $this->username;
        }

        $sql = 'SELECT COLUMN_NAME, DATA_TYPE, CHAR_LENGTH, DATA_PRECISION, DATA_LENGTH, DATA_DEFAULT, NULLABLE
            FROM ALL_TAB_COLUMNS
            WHERE UPPER(OWNER) = '.$this->escape(strtoupper($owner)).'
                AND UPPER(TABLE_NAME) = '.$this->escape(strtoupper($table));

        if (($query = $this->query($sql)) === FALSE)
        {
            return FALSE;
        }
        $query = $query->result_object();

        $retval = array();
        for ($i = 0, $c = count($query); $i < $c; $i++)
        {
            $retval[$i]            = new stdClass();
            $retval[$i]->name        = $query[$i]->COLUMN_NAME;
            $retval[$i]->type        = $query[$i]->DATA_TYPE;

            $length = ($query[$i]->CHAR_LENGTH > 0)
                ? $query[$i]->CHAR_LENGTH : $query[$i]->DATA_PRECISION;
            if ($length === NULL)
            {
                $length = $query[$i]->DATA_LENGTH;
            }
            $retval[$i]->max_length        = $length;

            $default = $query[$i]->DATA_DEFAULT;
            if ($default === NULL && $query[$i]->NULLABLE === 'N')
            {
                $default = '';
            }
            $retval[$i]->default        = $query[$i]->COLUMN_DEFAULT;
        }

        return $retval;
    }

    // --------------------------------------------------------------------

    /**
     * Error
     *
     * Returns an array containing code and message of the last
     * database error that has occured.
     *
     * @return    array
     */
    public function error()
    {
        /* oci_error() returns an array that already contains the
         * 'code' and 'message' keys, so we can just return it.
         */
        if (is_resource($this->curs_id))
        {
            return oci_error($this->curs_id);
        }
        elseif (is_resource($this->stmt_id))
        {
            return oci_error($this->stmt_id);
        }
        elseif (is_resource($this->conn_id))
        {
            return oci_error($this->conn_id);
        }

        return oci_error();
    }

    // --------------------------------------------------------------------

    /**
     * Insert batch statement
     *
     * Generates a platform-specific insert string from the supplied data
     *
     * @param    string    $table    Table name
     * @param    array    $keys    INSERT keys
     * @param     array    $values    INSERT values
     * @return    string
     */
    protected function _insert_batch($table, $keys, $values)
    {
        $keys = implode(', ', $keys);
        $sql = "INSERT ALL\n";

        for ($i = 0, $c = count($values); $i < $c; $i++)
        {
            $sql .= '    INTO '.$table.' ('.$keys.') VALUES '.$values[$i]."\n";
        }

        return $sql.'SELECT * FROM dual';
    }

    // --------------------------------------------------------------------

    /**
     * Truncate statement
     *
     * Generates a platform-specific truncate string from the supplied data
     *
     * If the database does not support the TRUNCATE statement,
     * then this method maps to 'DELETE FROM table'
     *
     * @param    string    $table
     * @return    string
     */
    protected function _truncate($table)
    {
        return 'TRUNCATE TABLE '.$table;
    }

    // --------------------------------------------------------------------

    /**
     * Delete statement
     *
     * Generates a platform-specific delete string from the supplied data
     *
     * @param    string    $table
     * @return    string
     */
    protected function _delete($table)
    {
        if ($this->qb_limit)
        {
            $this->where('rownum <= ',$this->qb_limit, FALSE);
            $this->qb_limit = FALSE;
        }

        return parent::_delete($table);
    }

    // --------------------------------------------------------------------

    /**
     * LIMIT
     *
     * Generates a platform-specific LIMIT clause
     *
     * @param    string    $sql    SQL Query
     * @return    string
     */
    protected function _limit($sql)
    {
        $this->limit_used = TRUE;
        return 'SELECT * FROM (SELECT inner_query.*, rownum rnum FROM ('.$sql.') inner_query WHERE rownum < '.($this->qb_offset + $this->qb_limit + 1).')'
            .($this->qb_offset ? ' WHERE rnum >= '.($this->qb_offset + 1) : '');
    }

    // --------------------------------------------------------------------

    /**
     * Close DB Connection
     *
     * @return    void
     */
    protected function _close()
    {
        oci_close($this->conn_id);
    }

}
